With increasing a population of aged generation, dementia is occupying large weight in care of the aged. Although many medicines have been developed in order to improve various types of dementia such as dysmnesia, they are not fully enough in the points of efficacy, persistence and side effect.
For example, the function of cholinergic nervous system in hippocampus, amygdala and cerebral cortex is depressed in brains of patients of Alzheimer's disease (Pope et al., Trans. Am. Neurol. Assoc., 89, 15 (1964), Bowen et al., Brain, 266, 558 (1976) and Davies et al., Lancet, ii, 1043 (1976)). The above-mentioned is considered to be firmly concerned with nosogenesis of the impairment of memorization or memory which is main symptom of Alzheimer's disease (Whitehouse et al., Science, 215, 1237 (1982)). Therefore, there is a possibility that these disturbances are improved by potentiating cholinergic nervous system. However, agonists of muscarinic cholinergic receptor which have been used up to date have high toxicity in spite of showing efficacy and therefore have not been practically used (Wettsein et al., Psychopharmacology, 84, 572 (1984) and Hollander et al., Biol. Psychiatry, 22, 1067 (1987)).
On the other hand, in a highly information-oriented society, there increase diseases due to mental repression. As one of such diseases, depression can be exemplified. Although there are many medicaments for depression, they are not fully satisfiable in the points of fast-acting property and side effect.
So, more effective and safe medicaments are required for the above-mentioned diseases.